Arcanine is a great Pokemon that can perform well in most situations.
Arcanine@ Expert Belt
Ability: Flash Fire
This is my personal favorite setup for Arcanine. You can choose either Flare Blitz or Flamethrower for your STAB move depending on if you want Arcanine to be a special or mixed sweeper. If you want him to be mixed, I would place his EVs as follows: 252 Atk, 252 SpAtk, 4 Spd. If not, I would place them like this: 252 SpAtk, 252 Spd, 4 Hp. Solarbeam gives you coverage against all of Arcanine's weaknesses and even without STAB the expert belt gives you the power you need to deal considerable damage to your opponents. Sunny Day is a no-brainer. It gets rid of the charge move for Solarbeam and strengthens your STAB move. It also increases the healing power of Morning Sun. Finally, Morning Sun will heal for the recoil of Flare Blitz and any other attacks Arcanine withstands.